This seamless, unpadded bra proved "comfortable enough to wear all day," says an A-cup runner. The stretchy blend of Merino wool, polyester, nylon, and spandex "feels soft and not constrictive." Because wool stays stink-free (even after multiple wearings), traveling runners packed just this one bra for an entire trip. Instead of seams, variations in the knit create separate, defined cups that testers found flattering. But it's warmer and bulkier than all-synthetic bras.

"I typically wear BodyGlide," says one A-cup tester, "but I didn't chafe at all in this bra, even when I skipped that preventive measure." The racerback design "felt very secure without digging in or being too tight," and the fast-wicking fabric kept her dry throughout a six-mile run in Florida humidity. Removable cups let you choose between modesty and breathability, and the ample support makes it a "go-to bra for harder workouts."

Thanks to separate molded cups, "It looks like I'm wearing a regular bra, not a uniboob sports bra," says one A-cup tester, who reports "no bounce on runs, and just a little bounce while jumping." The band and straps are both adjustable; testers preferred the cross-back configuration for its increased support and freedom of movement. Fine mesh on the back minimizes clamminess, but the padded cups "feel like a sweat barrier," says one wearer.

Removable molded cups are this bra's only frill. "They eliminate 'headlights' and add a nice bit of oomph for small-chested folks like me," says one B-cup tester. The rest is all business: Support is solid, and it kept testers comfortable through long speed workouts. Wide racerback straps and soft fabric prevent chafing, and a mesh lining wicks moisture fast. "The padding soaks up sweat more than the bra itself, so when it's really hot, I just take out the pads," says one runner.